I also have issues with Elusive. Elusive, fearsome and overwhelm should be a tad more expensive, maybe even just 1 more.
I would also like the introduction of a 'defender' mechanism. Not like in Gwent, something preventing the defender from being affected by any offensive abilities (elusive, fearsome, overwhelm, challenger, vulnerable...). They could not be able to attack (or not). But as Archangel said, that would make games longer and that is probably not their goal.
After a couple of days, I feel indeed that the direct damage is very strong, although not out of control. Maokai doesn't really bother me. What bothers me is that the tossing mechanics could toss champions, to make it riskier. Now it doesn't, whereas stealing cards from the opponent's deck can steal champions. Also, never been a fan of stealing, I would much rather have the cards make a copy of an enemy card.
Also, I fear the sea monsters may be too strong. They are pretty cheap and some have crazy effects, without even counting the deep mechanics. 'elusive + draw a card' on stike', 'obliterate an ennemy', 'add fearsome and -2 on ennemys' (which could be a champion). Those are already strong, so when combined with deep and the synergy allowing to draw/reduce costs.
For the rest, I like the mechanics so far. Plunder is interesting. I'd rather have it made on combat damage, to avoid cheap 'do 1 to nexus' combos but it's fun. Twisted fate, Gangplank, Swain, Fizz... The new champions are original and fun. The new frejlord one (can't remember her name) combined with Ashe will probably allow for crazy combos.
Anyway, since the devs seem pretty on top of it with bi-monthly patches, fixes, balances and watchlists, I hope to see some unbalances fixed but still enjoying it.